Since the 55BC campaign the southern part of Britain had been trading with Roman occupied Gaul, and paying
tribute which was at least as much as would have been paid had Rome occupied Britain.
By the 40s AD, the political situation within Britain was changing. The Catuvellauni tribe had taken over
the role of most important tribe in southern Britain from the Trinovantes. They had taken over the former
Trinovantian capital of Camulodunum (Colchester), and were expanding into Atrebates territory who were
ruled by the descendants of Julius Caesar's former ally Commius.
Prior to 43AD previous abortive campaigns had been planned by Augustus in 34BC, 27BC and 25BC but these had
been called off due to revolts in other parts of the Roman Empire. In 40AD Caligula had planned a campaign
but due to his ill health had called it off.
So in 43AD Claudius mounted an invasion force to re-instate Verica, the king of the Atrebates who had been
exiled due to the Catuvellauni invasion. Four legions, of about 20,000 men, plus about the same number of
auxiliaries were gathered in Itius Portus(Gesoriacum) most likely modern Boulogne. The legions involved
were the Legio II Augusta, Legio IX Hispana, Legio XIV Gemina and Legio XX Valeria Victrix.
The main invasion force commanded by Aulus Plautius crossed in three divisions with the most likely landing
being at Rutupiae (Richborough) in east Kent as at the time would have had a large natural harbour. Various
reports of the invasion imply that some of the forces may have also come from the Rhine region.
Togodumnus and Caratacus, sons of the late king of the Catuvellauni, Cunobeline lead the British defence, and
a large British force met the Romans at a river crossing assumed to be Rochester on the River Medway. The
battle raged for two days when Gnaeus Hosidius Geta, who probably led the IX Hispana was almost captured.
Recovering his push back he turned the battle so decisively that he was awarded the triumphus*, so the defeat
of the Britains must have been very severe.
The British were pushed back to the Thames and were pursued by the Romans across the river causing some Roman
losses in the marsh land of Essex. The Romans may have crossed via an existing bridge or built a temporary one
t cross by, and at least one division of Batavian troops swam across the river.
Togodumnus died shortly after the battle on the Thames and Claudius says he received the surrender of eleven
kings of Britain without further battle or bloodshed. Caratacus escaped and continued his resistance to Rome
further to the west.
* The triumphus - Roman triumph was a civil ceremony and religious rite of ancient Rome to publicly celebrate and
sanctify the success of a military commander who had led Roman forces to victory in the service of the state.